Changes in the microbiome along the invasion range of a successful invader, the signal crayfish. 16S crayfish microbiome

Increasing evidence denotes the role of microbiome in biological invasions, since it is known that microbes can affect the fitness of the host. We analyzed the microbiomes of different tissues (exoskeleton, hemolymph, hepatopancreas and intestine) of a successful freshwater invader, the signal crayfish, compared them to the environmental microbiome, and explored their changes along the invasion range. Exoskeleton, hepatopancreas and intestine microbiomes varied between invasion core and front populations, indicating that they may be partly determined by population density which was higher in the invasion core compared to invasion front. The highly diverse microbiome of exoskeletal biofilm was partly shaped by the environment (due to the similarity with sediment microbiome), and partly (due to the high proportion of exoskeleton-unique ASVs), by intrinsic crayfish parameters, including the core/front differences in population structure. Hemolymph had the most distinct microbiome compared to other tissues and differed between upstream (rural) and downstream (urban) river sections, indicating that its microbiome is potentially more driven by the effects of the abiotic environment. Our findings offer a first insight into microbiome changes during dispersal of a successful invader, and present a baseline for assessment of their contribution to invader’s overall health and its further invasion success.